The electrodeposition of coating compositions has become a fast growing industry. A wide variety of resinous compositions have been applied to obtain desirable results. The compositions utilized today may be either anionic in nature, that is, compositions which deposit at the anode, or cationic in nature, that is, compositions which deposit at the cathode. Many disadvantages have been encountered in employing anionic compositions, due in large part to their acidic nature; for example, anionic compositions tend to be sensitive to common types of corrosive attack, e.g., by salt, alkali, etc., and anionic deposition tends to place the uncured coating in proximity to metal ions evolved at the anode, thereby causing undesirable staining. Because of such undesirable characteristics there has been an increased interest in cationic compositions.
In the past it has been found that various amino monomers may be employed in the preparation of interpolymers which subsequently may be electrodeposited at the cathode to provide suitable coatings. See U.S. Pat. No. 3,454,482.
It is also known that aqueous compositions comprising acid-solubilized, imine-modified, carboxylic acid group-containing acrylic resins can be blended with a blocked isocyanate and subsequently deposited at the cathode, to provide suitable coating compositions, see U.S. Pat. application Ser. No. 47,860, filed June 19, 1970, now U.S. Pat. No. 3,679,564. Likewise, it is known that blends of blocked organic polyisocyanates with polyamide amine resins, i.e., Versamid 115, which is a condensation product of dimerized linoleic acid and diethylene triamine, can be electrodeposited at the cathode to produce coatings having highly desirable properties.